U.S. Pat. Nos. 2,507,858, 2,541,520 and 4,216,783 disclose devices for measuring the strength of contractile muscles. The latter patent is particularly concerned with providing a visual indication of the strength of vaginal muscles. The basic construction of such a muscle monitor includes a hollow, flexible, compressible bulb assembly insertable into the vagina and a flexible tube connecting the bulb with a gauge for measuring the increase in internal air pressure which results from the patient's contraction on the bulb. The monitor is useful as a biofeedback device for measuring the strength of the pubococcygeus (PC) muscle for the purpose of aiding the user to increase the degree and strength of control exercised over that muscle.
In accordance with the present invention, there is provided a disposable sheath or shield which can be placed over the bulb portion of the monitor prior to use and subsequently discarded. The use of the sheath is particularly advantageous to the doctor or technician in that it allows the doctor or technician to measure and record PC muscle strength as a routine office procedure during patient visits. As the disposable sheath serves as a protective barrier between the vaginal tissues and the parts of the monitor which would otherwise come in contact with the vaginal tissues, it is not necessary to sterilize or replace those parts of the device after each use.
The sheath is made of thin latex or other flexible, slightly elastic material and is generally complementary in size and shape to the bulb and adjacent portion of the bulb. It fits the exterior of the bulb snugly so as not to be dislodged during use but it is easily removed when desired.